This Core is responsible for all epidemiological, statistical, and data management aspects of the Program Project. The Section of Clinical Epidemiology, including the Rochester Epidemiology Project, provides the nucleus for the population-based Project l by assuming complete ascertainment of all Clinical aspects pertaining to the residents of Olmsted County. This includes coordination of our access to the records of other patient core providers, determination of residency, and ongoing maintenance of county demographic, survival, and disease rate databases. The Section of Biostatistics provides statistical expertise including state of the art analysis and data management resources, but especially for Projects I, III, and IV which assess factors across the patient population, with less involvement in the projects focused primarily on cell lines. The Survey Research Center, within the Section of Biostatistics, provides expertise in the contract and follow-up of Mayo patients and will be particularly important to Project I. The existence of this Core assures a uniform plan of protocol design, data handling, and statistical analysis and further assures that appropriate resources are available to all investigators.